/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
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 *  http://www.apache.org/licenses/LICENSE-2.0
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 * Unless required by applicable law or agreed to in writing, software
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 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Other licenses:
 * -----------------------------------------------------------------------------
 * Commercial licenses for this work are available. These replace the above
 * ASL 2.0 and offer limited warranties, support, maintenance, and commercial
 * database integrations.
 *
 * For more information, please visit: http://www.jooq.org/licenses
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package org.jooq.impl;

import static org.jooq.impl.DSL.count;
import static org.jooq.impl.DSL.exists;
import static org.jooq.impl.DSL.notExists;
import static org.jooq.impl.DSL.one;
import static org.jooq.impl.DSL.row;
import static org.jooq.impl.DSL.select;
import static org.jooq.impl.Keywords.K_NOT;
import static org.jooq.impl.Keywords.K_UNIQUE;
import static org.jooq.impl.Tools.visitSubquery;

import org.jooq.Condition;
import org.jooq.Context;
import org.jooq.Field;
import org.jooq.Select;
import org.jooq.Table;

/**
 * @author Knut Wannheden
 */
final class UniqueCondition extends AbstractCondition {

    private final Select<?> query;
    private final boolean   unique;

    UniqueCondition(Select<?> query, boolean unique) {
        this.query = query;
        this.unique = unique;
    }

    @Override
    final boolean isNullable() {
        return false;
    }

    @Override
    public final void accept(Context<?> ctx) {
        switch (ctx.family()) {
            case H2:
                if (!unique)
                    ctx.visit(K_NOT).sql(' ');

                ctx.visit(K_UNIQUE).sql(' ');
                visitSubquery(ctx, query);
                break;

            default:
                Table<?> queryTable = query.asTable("t");
                Field<?>[] queryFields = queryTable.fields();
                Select<?> subquery = select(one())
                    .from(queryTable)
                    .where(row(queryFields).isNotNull())
                    .groupBy(queryFields)
                    .having(count().gt(one()));

                ctx.visit(unique ? notExists(subquery) : exists(subquery));
                break;
        }
    }

    @Override
    public final Condition not() {

        // TODO: [#7362] [#10304] Find a better way to prevent double negation and unnecessary parentheses
        return unique ? new UniqueCondition(query, false) : super.not();
    }
}
